176 



INVERTEBRATE ANIMALS. 



insect comes to the surface, and which convey air to tlie tracheae. 

 Though active, the pupa does not eat ; and when the time comes for 

 the completion of the metamorphosis it approaches the surface, above 

 which it raises its back. The skin then splits dorsally, and, drying. 



, 122. — The common Gnat (Culex pipuiis). A, A few of the eggs, attached together 

 to form a raft, which floats on the water ; B, The larva, su.spended in the water 

 head downwards, and showing the antennje (a), the terminal respiratory tube (r), 

 and the fins attached to tlie extremity of tlie body (/) ; C, The pupa, with the two 

 respiratory tubes attached to the tliorax ; D, The adult'inspct, with the well- 

 developed front wings, tlie rudimentary hind wings or " lijilancers" (h), the 

 antennis (a), and the proboscis (p). All the figures are greatly enlaj-ged. 



forms a boat, in which the insect floats until its wings are fit 

 for use. 



The J)ipti'ra constitute one of the largest orders of insects ; the 

 House-flies and Flesh-flies {Musni), the Gnats and Mosquitoes 

 (Ciilicii.he), the Crane-flies (Tipula), the Forest-flies (Hippobosca), 

 and the Gad-flies (Tabanidce) constituting good examples. 



Order X. Lepidoptera. 



This well-known and most beautiful of all the orders of insects 

 comprises the Butterflies and Moths, the former being active by day 

 {diurnal), and the latter mostly towards twilight (crepuscular), or 

 at night {nocturnal). In all the Lepidoptera the mouth of the adult 

 insect is purely suctorial, and is provided with a spiral trunk fitted 

 for imbibing the juices of flowers, and formed out of the elongated 



